Fuel oil such as home heating fuels, automotive fuel oils, gas turbine fuels, and heavy fuels used for industrial heating and for slow and medium speed diesel engines, as well as lubricating oils for engines and other uses, are susceptible to deterioration during storage, resulting in the formation of insoluble sludge, sediment and discoloration. A wide variety of additives, especially various amine compounds have been proposed and used to prevent discoloration and sediment formation by retarding the formation of discolorants or insoluble materials during storage or when thermally stressed. One example is N,N-dimethylcyclohexylamine as disclosed in U.S. Pat. No. 3,490,882. Other additives such as copolymers characterized by having basic amino groups appended to the main polymer chain are known as disclosed in U.S. Pat. No. 3,186,810 and 2,737,452 for use in fuel oils and in U.S. Pat. No. 2,737,496 for use in lubricating oils. Such copolymers have been comprised of such monomers as lauryl methacrylate, diethylaminoethyl methacrylate, styrene and other alkyl methacrylates and amino methacrylates. Although useful, such additives do not provide a complete solution to the problems and the need for improved additives remains.
This invention is concerned with improved additives for stabilizing fuel and lubricating oil compositions against deterioration during storage and stabilized oil compositions containing the additives.
Also U.S. Pat. No. 4,656,226 discloses certain block copolymer dispersants containing methacrylate and acrylate monomeric units wherein a polymer block may contain certain polar groups, among which are mentioned primary, secondary and tertiary aliphatic amines, as substituents which are bonded to the polymer block. A general disclosure is included that such dispersants can be used as additives for oil and fuel.
An object of this invention is to improve the stability of petroleum distillate oils against deterioration such as the formation of insoluble sludge, sediment, gum and discoloration. A further object is to provide a novel improved additive for stabilizing distillate hydrocarbon fuel oils.